Marcu 15, 1901.] 
ward into Alaska and southward to Cali- 
fornia. 
In the later time of the Carboniferous, 
however, the volcanic forces declined in 
their activity, and a great thickness of 
caleareous marine deposits occurred with 
little interruption of any kind. The area 
of land to the eastward was probably in- 
creased, for there is some evidence to show 
a first gentle uprising in the Laramide re- 
gion at this time (or at least a cessation 
of subsidence), and no late Carboniferous 
strata have so far been found there. 
No separate record for the Permian has 
yet been found in this part of the continent, 
but it must be remembered that, in view of 
the scanty character of the paleontological 
evidence, strict taxonomic boundaries can 
seldom be drawn. At about this time, 
however, very important changes occurred, 
for in the Triassic a great part of what is 
now the inland plain of the continent is 
found to have become the bed of a sea shut 
off from the main ocean, in which red rocks 
with salt and gypsum in some places were 
laid down. The northern part of this sea 
appears to have extended into the Canadian 
region for a short distance, covering the 
southern portion of the Laramide area. 
Farther north must have been the land 
boundary of this sea, and beyond this an 
extension of the Pacific ocean which swept 
entirely across the Cordillera. In the 
southern part of British Columbia, how- 
ever, this ocean found its shore against the 
Gold ranges of the Archean axis, where 
the preceding Carboniferous beds had al- 
ready been upturned and subjected to denu- 
dation. The Laramide region was not 
affected by volcanic action at this time, but 
vulcanism on a great scale was resumed in 
the entire western part of the Cordillera 
that had previously been similarly affected 
in the Carboniferous, and the ordinary 
marine sediments there form interealations 
only in a great mass of voleanic products, 
SCIENCE. 
403 
probably in large part the result of sub- 
marine eruptions. 
Such definite indications as exist of the 
Jurassic must, as already noted, be consid- 
ered as physically attached to the Triassic 
of the interior plateau of British Columbia. 
It is probable that the greater part of the 
Jurassic period was characterized by re- 
newed orogenic movements and by denuda- 
tion, for when we are next able to form a 
connected idea of the physical conditions 
of the region these are found to have been 
profoundly modified. 
It is to about this time that the elevation 
of the Sierra Nevada and some other moun- 
tain systems in the western states is at- 
tributed. In the region here particularly 
described, the Triassic and older rocks of 
the Vancouver range, or that forming Van- 
couver and the Queen Charlotte islands, 
were upturned, while a similar movement 
affected the zone now occupied by the Brit- 
ish Columbia Coast ranges. These may 
not have been elevated into a continuous 
mountain system and barrier to the sea, 
but in any case the ranges then formed 
were, before the beginning of the Creta- 
ceous period, largely broken down by de- 
nudation, so that the underlying granitic 
rocks supplied abundant arkose material 
to some of the lowest Cretaceous beds. 
It is also probable that subsidence marked 
the close of the Jurassic, for in southern 
British Columbia the Pacific of the Harlier 
Cretaceous extended more or less continu- 
ously across the line of the Coast ranges, 
finding its shore not far to the east of this 
line. Farther north, although not without 
insular interruptions, it spread over the 
entire width of the Cordilleran belt, repeat- 
ing the conditions found in the Triassic, 
but with the difference that it extended far 
to the south along the axis of the Laramide 
geosyncline, in which rapid subsidence had 
been renewed. In this early Cretaceous 
sea and along its margins and lagoons the 
